accessing-pieces-arrays/script.rst
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    35 arrays, get rows and columns and other chunks of arrays using
    35 arrays, get rows and columns and other chunks of arrays using
    36 slicing and striding. 
    36 slicing and striding. 
    37 
    37 
    38 {{{ switch back to the terminal }}}
    38 {{{ switch back to the terminal }}}
    39 
    39 
    40 .. #[[Anoop: context switch, switch to next slide should be added]]
       
    41 
       
    42 As usual, we start IPython, using 
    40 As usual, we start IPython, using 
    43 ::
    41 ::
    44 
    42 
    45   ipython -pylab 
    43   ipython -pylab 
       
    44 
       
    45 
       
    46 {{ Show the slide with the arrays, A and C }}
    46 
    47 
    47 Let us have two arrays, A and C, as the sample arrays that we will
    48 Let us have two arrays, A and C, as the sample arrays that we will
    48 use to work through this tutorial. 
    49 use to work through this tutorial. 
    49 
    50 
    50 ::
    51 ::
    67 To access, the element 34 in A, we say, 
    68 To access, the element 34 in A, we say, 
    68 
    69 
    69 ::
    70 ::
    70 
    71 
    71   A[2]
    72   A[2]
    72 
       
    73 .. #[[Anoop: should be A[2], corrected it]]
       
    74 
    73 
    75 Like lists, indexing starts from 0 in arrays, too. So, 34, the
    74 Like lists, indexing starts from 0 in arrays, too. So, 34, the
    76 third element has the index 2. 
    75 third element has the index 2. 
    77 
    76 
    78 Now, let us access the element 34 from C. To do this, we say
    77 Now, let us access the element 34 from C. To do this, we say
   132   
   131   
   133   C[:, 2]
   132   C[:, 2]
   134 
   133 
   135 Following is an exercise that you must do. 
   134 Following is an exercise that you must do. 
   136 
   135 
   137 .. #[[Anoop: add context switches, switch to next slide]]
   136 {{ show slide containing Question 1}} 
   138 
   137 
   139 %%1%% Change the last column of C to zeroes. 
   138 %%1%% Change the last column of C to zeroes. 
   140 
   139 
   141 Please, pause the video here. Do the exercises and then continue. 
   140 Please, pause the video here. Do the exercises and then continue. 
   142 
   141 
   152 
   151 
   153 gives the whole of A. 
   152 gives the whole of A. 
   154 
   153 
   155 Following is an exercise that you must do. 
   154 Following is an exercise that you must do. 
   156 
   155 
   157 .. #[[Anoop: add context switches, switch to next slide]]
   156 {{ show slide containing Question 2}} 
   158 
   157 
   159 %%2%% Change ``A`` to ``[11, 12, 13, 14, 15]``. 
   158 %%2%% Change ``A`` to ``[11, 12, 13, 14, 15]``. 
   160 
   159 
   161 Please, pause the video here. Do the exercises and then continue. 
   160 Please, pause the video here. Do the exercises and then continue. 
   162 
   161 
   198 
   197 
   199   I 
   198   I 
   200 
   199 
   201 at the prompt, and see that an array is displayed. 
   200 at the prompt, and see that an array is displayed. 
   202 
   201 
   203 To check the dimensions of any array, we can use the method
   202 To check the dimensions of any array, we can use ``.shape``. We say
   204 shape. We say
       
   205 
       
   206 .. #[[Anoop: method is a function and .shape is a tuple, so it can be named
       
   207    as value or something instead of the term method.]]
       
   208 
   203 
   209 ::
   204 ::
   210 
   205 
   211   I.shape 
   206   I.shape 
   212 
   207 
   240 
   235 
   241   C[2, 0:3]
   236   C[2, 0:3]
   242 
   237 
   243 Following is an exercise that you must do. 
   238 Following is an exercise that you must do. 
   244 
   239 
   245 .. #[[Anoop: add context switches, switch to next slide]]
   240 {{ show slide containing Question 3 }} 
   246 
   241 
   247 %%3%% First, obtain the elements [22, 23] from C. Then, obtain the
   242 %%3%% First, obtain the elements [22, 23] from C. Then, obtain the
   248 elements [11, 21, 31, 41] from C. Finally, obtain the elements [21,
   243 elements [11, 21, 31, 41] from C. Finally, obtain the elements [21,
   249 31, 41, 0]. 
   244 31, 41, 0]. 
   250 
   245 
   251 Please, pause the video here. Do the exercises and then continue. 
   246 Please, pause the video here. Do the exercises and then continue. 
   252 
   247 
   253 .. #[[Anoop: add context switches, switch to next slide]]
   248 {{ show slide containing Solution 3 }}
   254 
   249 
   255 ::
   250 ::
   256 
   251 
   257   C[1, 1:3] 
   252   C[1, 1:3] 
   258 
   253 
   284 gives the elements [21, 31, 41, 0]. If we skip both the indexes,
   279 gives the elements [21, 31, 41, 0]. If we skip both the indexes,
   285 we get the slice from end to end, as we already know. 
   280 we get the slice from end to end, as we already know. 
   286 
   281 
   287 Following is an exercise that you must do. 
   282 Following is an exercise that you must do. 
   288 
   283 
   289 .. #[[Anoop: add context switches, switch to next slide]]
   284 {{ show slide containing Question 4 }} 
   290 
   285 
   291 %%4%% Obtain the elements [[23, 24], [33, -34]] from C. 
   286 %%4%% Obtain the elements [[23, 24], [33, -34]] from C. 
   292 
   287 
   293 Please, pause the video here. Do the exercises and then continue. 
   288 Please, pause the video here. Do the exercises and then continue. 
   294 
   289 
   295 .. #[[Anoop: add context switches, switch to next slide]]
   290 {{ show slide containing Solution 4 }} 
   296 
   291 
   297 ::
   292 ::
   298 
   293 
   299   C[1:3, 2:4] 
   294   C[1:3, 2:4] 
   300 
   295 
   316 
   311 
   317   imshow(I[:150, :150])
   312   imshow(I[:150, :150])
   318 
   313 
   319 Following is an exercise that you must do. 
   314 Following is an exercise that you must do. 
   320 
   315 
   321 .. #[[Anoop: add context switches, switch to next slide]]
   316 {{ show slide containing Question 5 }} 
   322 
   317 
   323 %%5%% Obtain the square in the center of the image.
   318 %%5%% Obtain the square in the center of the image.
   324 
   319 
   325 Following is an exercise that you must do. 
   320 Following is an exercise that you must do. 
   326 
   321 
   327 .. #[[Anoop: add context switches, switch to next slide]]
   322 {{ show slide containing Solution 5 }} 
   328 
   323 
   329 ::
   324 ::
   330 
   325 
   331   imshow(I[75:225, 75:225])
   326   imshow(I[75:225, 75:225])
   332 
   327 
   357 
   352 
   358   C[1::2, ::2] 
   353   C[1::2, ::2] 
   359 
   354 
   360 gives the elements, [[21, 23, 0], [41, 43, 0]]
   355 gives the elements, [[21, 23, 0], [41, 43, 0]]
   361 
   356 
   362 .. #[[Anoop: I think you forgot to "add switch to next slide" context
   357 {{ show slide containing Question 6 }} 
   363    switch, I think it will be better you review the scripts(all) for
       
   364    context switches and add them.]]
       
   365 
   358 
   366 Following is an exercise that you must do. 
   359 Following is an exercise that you must do. 
   367 
   360 
   368 %%6%% Obtain the following. 
   361 %%6%% Obtain the following. 
   369 [[12, 0], [42, 0]]
   362 [[12, 0], [42, 0]]
   370 [[12, 13, 14], [0, 0, 0]]
   363 [[12, 13, 14], [0, 0, 0]]
   371 
   364 
   372 Please, pause the video here. Do the exercises and then continue. 
   365 Please, pause the video here. Do the exercises and then continue. 
       
   366 
       
   367 {{ show slide containing Solution 6 }} 
   373 
   368 
   374 ::
   369 ::
   375 
   370 
   376   C[::3, 1::3]
   371   C[::3, 1::3]
   377 
   372 
   408 have learnt to access parts of arrays, specifically individual
   403 have learnt to access parts of arrays, specifically individual
   409 elements, rows and columns and larger pieces of arrays. We have
   404 elements, rows and columns and larger pieces of arrays. We have
   410 also learnt how to modify arrays, element wise or in larger
   405 also learnt how to modify arrays, element wise or in larger
   411 pieces.
   406 pieces.
   412 
   407 
   413 .. #[[Anoop: I think in the summary slide it is better to use single &
   408 {{{ Show the "sponsored by FOSSEE" slide }}}
   414    multi dimensional arrays instead of 1D and Multi dimensional arrays.]]
   409 
   415 
   410 This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India
   416 .. #[[Anoop: switch to thank you slide, added comment as it most probably
   411 
   417    won't be noticed]]
   412 Hope you have enjoyed and found it useful.
   418 
   413 Thank you!
   419 Thank You!
       
   420 
   414 
   421 .. 
   415 .. 
   422    Local Variables:
   416    Local Variables:
   423    mode: rst
   417    mode: rst
   424    indent-tabs-mode: nil
   418    indent-tabs-mode: nil